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Re: [PATCH, middle-end/RTL, i386]: Simplify nested VEC_SELECT RTX


On 7/13/07, Uros Bizjak <ubizjak@gmail.com> wrote:
> Hello!
>
> This patch optimizes VEC_SELECT nested RTL expressions (with optional
> VEC_CONCAT), when top VEC_SELECT extracts scalar operand.
>
> Currently, following testcase
>
> --cut here--
> int fooSI_1(__v4si *val)
> {
>   return __builtin_ia32_vec_ext_v4si(*val, 1);
> }
>
> int fooSI_2(__v4si *val)
> {
>   return __builtin_ia32_vec_ext_v4si(*val, 2);
> }
> --cut here--
>
> compiles with '-O2 -msse (-fomit-frame-pointer)' into:
>
> fooSI_2:
>         subl    $4, %esp
>         movl    8(%esp), %eax
>         movdqa  (%eax), %xmm0
>         punpckhdq       %xmm0, %xmm0
>         movd    %xmm0, (%esp)
>         movl    (%esp), %eax
>         addl    $4, %esp
>         ret
>
> fooSI_1:
>         subl    $4, %esp
>         movl    8(%esp), %eax
>         pshufd  $85, (%eax), %xmm0
>         movd    %xmm0, (%esp)
>         movl    (%esp), %eax
>         addl    $4, %esp
>         ret
>
> Attached patch simplifies this into:
>
> fooSI_2:
>         movl    4(%esp), %eax
>         movl    8(%eax), %eax
>         ret
>
> fooSI_1:
>         movl    4(%esp), %eax
>         movl    4(%eax), %eax
>         ret
>
> Similar effects can be obtained for SFmode operands.
>
> Patch was bootstrapped and regression tested on i686-pc-linux-gnu.

This is ok with the added comment.

Thanks,
Richard.

> 2007-07-13  Uros Bizjak  <ubizjak@gmail.com>
>
>         PR target/32661
>         * simplify-rtx.c (simplify_binary_operation_1) [VEC_SELECT]:
>         Simplify nested VEC_SELECT (with optional VEC_CONCAT operator as
>         operand) when top VEC_SELECT extracts scalar element.
>         * config/i386/sse.md (*vec_extract_v4si_mem): New.
>         (*vec_extract_v4sf_mem): Ditto.
>
> testsuite/ChangeLog:
>
> 2007-07-13  Uros Bizjak  <ubizjak@gmail.com>
>
>         PR target/32661
>         * gcc.target/i386/pr32661.c: New test.
>
> OK for mainline (patch needs middle-end/RTL approval) ?
>
> Uros.
>
>


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